This invention relates to a method and apparatus for remote calibration of a raster or stroke written video display.
Video display devices that have the ability to display either raster scanned information or stroke written information are called hybrid displays. Hybrid displays are usually calibrated by registering the raster and stroke display beams in relation to one another. In addition, both the stroke and raster circuits need to be calibrated so that each display type has the same point of reference on the screen. Registration and calibration is presently accomplished by the manual adjustment of potentiometers or the use of hand selected resistors.
To be effective, the adjustment of registration potentiometers and resistors must occur in a display system that is under power. This poses serious health and safety risks to those working on and around the display. For example, voltage in the powered display may be 25,000 volts or more. In addition, it is possible to damage the display device by the introduction of foreign materials and objects while the display is exposed and powered.
Periodically, raster and stroke displays need recalibration. Recalibration similarly requires the adjustment of a plurality of potentiometers. Typically the potentiometers needing adjustment are not easily accessible to a technician on display unit since the display unit is usually environmentally sealed.